1. Field
Embodiments of the present disclosure relate to a robot cleaner to acquire information about the surface of an object and to control operation based on the acquired information, and a control method thereof.
2. Description of the Related Art
Lately, with developments in electronic technology, such as computing technology, sensing technology, and communication technology, technology for automating human tasks in specific environments is rapidly advancing.
Accordingly, studies into autonomous mobile devices that autonomously travel without user manipulation are being actively conducted. The autonomous mobile devices include an industrial robot, a domestic robot, a service robot, and a security robot, all of which perform human tasks and offer various kinds of convenience for humans.
Also, in order to improve the traveling performance of the autonomous mobile devices, technology for building a map of a target area and for recognizing a location, technology for detecting obstacles, stair gaps, and the like and avoiding the obstacles, etc. are being actively developed.
Since the traveling performance of an autonomous mobile device depends on the composition and condition of a floor, technology for acquiring information about a floor surface, such as the material of the floor surface or the contaminated state of the floor surface, is needed.
A robot cleaner, which is a type of a domestic robot, can clean a floor such as a wooden floor with an appropriate suction force even without taking the material or condition of the floor surface into consideration. When the robot cleaner cleans a carpet, however, it may not clean the carpet appropriately since wheels often get stuck into the carpet or a brush fails to smoothly move. In other words, since the traveling performance and functions of the robot cleaner depend on the material, condition, etc. of a floor surface, technology for detecting the state of a floor surface is demanded.
Generally, the robot cleaner detects the surface state of a floor based on data sensed by an ultrasonic sensor or an infrared sensor.
The ultrasonic sensor calculates a distance to a floor using velocity at which ultrasonic waves are transmitted in the air. In the case of using the ultrasonic sensor, there is a problem that it is difficult to accurately distinguish materials of various types of objects since a floor material is determined only using the intensity of a reflected ultrasonic wave. Also, when the ultrasonic sensor is used at a short distance to a floor, the ultrasonic sensor may fail to properly operate due to composite waves.
The infrared sensor measures an amount of radiation from emitted light. The infrared sensor has a simple structure, and can be fabricated at low cost, compared to Position Sensing Device (PSD) sensors. However, optical members included in the infrared sensor are vulnerable to scratches, contaminants such as dust, etc. Moreover, cleaning the surface of the infrared sensor is not easy, and the infrared sensor may operate incorrectly when it is exposed to hard light. For these reasons, it is difficult to maintain and manage the infrared sensor. Furthermore, the infrared sensor has relatively low accuracy in detecting the surface condition of a floor.